The authors investigated the effect of weekly iron supplementation with and without deworming upon hemoglobin in a double-blind, placebo-controlled field trial conducted in the West Javanese village of Setia Asih. 289 children aged 2-5 years were randomly divided into three equal-sized treatment groups for the study. Groups one and two received 30 mg iron once weekly, while group three received a placebo. Group one also received anthelminthic treatment. Supplements were administered by the mothers who were taught about iron deficiency beforehand. In the iron-supplemented groups, the prevalence of anemia decreased from 37.2% to 16.2% and hemoglobin increased by an average of 6.9 +or- 9.8 g/l. However, hemoglobin increased only 1.9 +or- 8.0 g/l in the placebo group. No subjects had hookworms, so anthelminthic treatment had no additional effect.